The chemical equation below represents an acid-base reaction.

Question

NO2-( aq) + H2O( l) → HNO2( aq) + OH -( aq)

The NO2-( aq) acts as...

A.
Brønsted Lowry acid
B.
Brønsted Lowry base
C.
Arrhenius acid
D.
Arrhenius base

Answer 1

In the given reaction:

$${\text{{NO}}}_2^{-}(aq)+{\text{{H}}}_2\text{{O}}(l)\to {\text{{HNO}}}_2(aq)+{\text{{OH}}}^{-}(aq)$$

the ${\text{{NO}}}_2^{-}$ ion is acting as a proton acceptor because it takes a proton (H${}^{+}$) from water (${\text{{H}}}_2\text{{O}}$), which results in the formation of nitrous acid (${\text{{HNO}}}_2$) and hydroxide ions (${\text{{OH}}}^{-}$).

According to the Brønsted-Lowry acid-base theory:

• A Brønsted-Lowry acid is a substance that donates a proton (H${}^{+}$), while
• A Brønsted-Lowry base is a substance that accepts a proton (H${}^{+}$).

Since ${\text{{NO}}}_2^{-}$ is accepting a proton, it acts as a Brønsted-Lowry base.

Therefore, the correct answer is:

B. Brønsted-Lowry base.